DELTA — The Federal Aviation Administration determined Friday that a series of power lines recently constructed just north of the Blake Field airport in Delta pose a hazard to air navigation and could impair airport efficiency.

The FAA said Tri-State Generation and Transmission Association Inc. constructed the power line “prior to completion of this aeronautical study and did not provide the FAA any opportunity to identify the possible IFR (instrument flight rules) impacts on a new plan-on-file GPS-based instrument approach and did not provide an opportunity for negotiation and mitigation.”

The 12.9-mile, $21 million project was completed in November and includes two new electric substations, according to Tri-State. The lines are linked to a transmission route between Montrose and Grand Junction.

The Delta County Commission granted Tri-State approval for the lines last year with stipulations that the company adhere to all federal and state regulations.

The FAA has no enforcement authority to make Tri-State change or alter the route to adhere to federal safety standards. That power rests with the county commission.

Knight said Friday that findings in the report will be presented to the county commission during its regularly scheduled meeting Monday.

Attempts to reach Tri-State for comment were not successful Friday.

The power lines are not in operation but will transmit 115 kilovolts when energized, according to Tri-State.

The transmission route runs one-half mile northwest of the Blake Field runway, according to airport manager Mark Husman. Ten of the poles have been put on a hill that rises 100 feet higher than the runway, and at 50 feet tall, the poles exceed the height limit set forth by the FAA.

The FAA report identified nine power poles exceeding FAA height standards and said they could impact arrival, departure and en-route procedures for aircraft operating under visual flight regulations or VFR.

Pilots began noticing the construction last fall and immediately voiced safety concerns to county officials. The FAA said it had gotten calls and letters from dozens of concerned pilots and aviation organizations.

A company that wants to build a structure near an airport must notify the FAA prior to its construction. The company can complete the Notice Criteria Tool on the FAA’s website, which helps an applicant determine whether notice to the FAA is warranted.

“Following concerns expressed by the Delta County and Blake Field Airport, Tri-State re-evaluated the location data entered into the Notice Criteria Tool last July and determined, after consulting with the FAA, that the latitude and longitude information for the transmission line project was improperly converted before being entered into the online tool,” Tri-State spokeswoman Sarah Carlisle said in a written statement.

The FAA could require Tri-State to install red warning lights on top of the poles and lighted signal balls on the wires.

“Even if the towers themselves have obstruction lighting, the transmission lines between the towers would be invisible to a pilot at night or in many conditions even during daylight. Under these circumstances, a VFR pilot maneuvering within normal tolerances for landing or after takeoff is at high risk of impacting either the towers or the transmission lines between the towers. Non-local pilots or low-experience pilots that may be unfamiliar with the unique terrain features around Blake Field are at even higher risk,” the report said.

Carlisle said Tri-State acted swiftly when the problem was identified, and it has worked diligently with the FAA to get a determination and resolve the issue in a timely manner.

The FAA concluded if the power poles aren’t altered or removed, new flight standards would need to be implemented. The report said the poles could impact airport capacity and efficiency and affect the usable length of an existing or planned runway.

The report said the determination becomes final on April 9 unless a petition is filed to challenge it.